The present invention relates in general to telecommunications traffic monitoring, and, more specifically, to a tool for assisting network monitoring personnel to assess traffic blockage for a plurality of switches in the network.
Telecommunications systems such as the public switched telephone network and cellular wireless networks include switches for forwarding traffic to the appropriate destinations. The communication channels for carrying traffic between switches are known as trunks. Trunks may interconnect switches to other switches or to other traffic nodes such as a base station controller in a wireless cellular system.
Trunks are also sometimes referred to as circuits. As used herein, trunk refers to any single transmission channel between two points. A trunk group is one or more trunks that connect the same two points (e.g., switches or nodes) and are connected in such a way that if a call is routed to the trunk group and a free circuit is available in the trunk group, then the call will be routed on the free circuit. The trunk groups included in a network are laid out between the switches and nodes in a quantity that provides the capacity needed to optimally handle traffic loads experienced within the network. A control center is provided within the telecommunications network for monitoring network elements (e.g., detecting failures of switches and trunks) and managing network performance.
In order to assist in handling variable traffic loads between origination and destination switches for all the simultaneous calls being forwarded within the network, alternate routes are established between the pairs of switches. Typically, each separate route from one switch to another switch is defined according to a hierarchy of trunk groups leading from an origination switch that may be used to establish a connection to the destination switch (possibly via an intermediate switch). This hierarchy is stored in a routing table. A higher priority trunk group (e.g., a trunk group providing a direct connection to the destination) is listed first in the routing table. When attempting to establish a connection for a new call, if the higher priority trunk group does not have a free circuit then lower priority trunk groups are sequentially identified until either a free circuit is found or until a final trunk group in the routing table has been checked. If the final trunk group cannot provide a free circuit, then the call is blocked.
Excessive call blockage must be detected at the control center so that changes in the network configuration can be made to reduce blockage. Switches compile performance data continuously during their operation and the control center collects the data periodically for analysis. In addition, alarm messages are sent by the switches upon the occurrence of certain failures or conditions. Due to the large amount of data that is accumulated at the control center for analysis, detection of specific blockage issues is difficult and time consuming. Furthermore, a certain amount of blocked calls are always present and are not necessarily an indication of a significant traffic issue. Therefore, it would be desirable to provide a data analysis tool that can better identify traffic problems that need attention of the control center technicians.